1. Field of the Invention
The present invention is generally in the field of semiconductors. More specifically, the invention is in the field of semiconductor circuits and amplifiers.
2. Related Art
Amplifiers based on bipolar technology are widely used in a variety of applications, including wireless communication, such as radio frequency (“RF”) communication, for example. Bias circuits perform an important function by supplying a base bias current to bipolar transistors for controlling the operation modes of the bipolar transistors in amplifiers.
Digital mode control circuits have been used to reduce current and power consumption for low power mode operation in high-power amplifiers. Digital mode controls circuits, however, have a single and abrupt transition point from low power mode to high power mode, which substantially limits current consumption savings, particularly during very low power mode operation.
In an effort to improve current consumption savings, CMOS circuitry in an additional CMOS die have been employed in high-power amplifiers. With this arrangement, CMOS circuitry can provide improved analog control voltage into the base bias of the bipolar transistor of the amplifier, resulting in a substantially continuous quiescent current transition from a very low power level. In this way, current consumption can be greatly reduced even at low power modes. The addition of a separate CMOS die to the amplifier, however, results in increased device size and increased costs, both of which are undesirable.
Accordingly, there is a strong need in the art for a quiescent current control circuit for high-power amplifiers.